I. Field of the Invention
This invention relates generally to endoscopic application of bio-materials to target tissue in the course of a laparoscopic surgical procedure, and more particularly to an endoscopic spray applicator system design to mix two non-homogeneous liquids and to allow the resulting mixture to be applied thinly and evenly by spraying, on a difficult to reach treatment site, such as subcutaneously or within the body through an endoscopic cannula.
II. Discussion of the Prior Art
Tissue adhesives have long been recognized for their potential to hasten wound healing, reduce post-operative complications and decrease the need for drains following surgery. Typically, such adhesives have been prepared on the day of surgery from the patient's own blood. A quantity of blood would be drawn from the patient just prior to surgery and in a centrifugation process, natural clotting factors are isolated and concentrated for application on to the surgical wound while the remaining red blood cells were then reinjected or autotransfused back into the patient's bloodstream.
Fibrin sealant is a tissue adhesive that mimics the body's own natural clotting mechanism. Two basic components make up fibrin sealant, namely, fibrinogen and thrombin. Because fibrin sealant is derived from blood products, it is associated with viral disease transmission. To reduce the risk of viral-disease transmission from pooled plasma sources of fibrinogen, various viral inactivation methods are employed in commercial fibrin sealants. Blood banks often produce fibrinogen from screened, single-donor sources or use autologous fibrinogen. Currently, bovine thrombin is most often used, although methods for producing human thrombin or recombinant thrombin are being developed. Fibrin sealants can be used in a variety of surgical applications to enhance hemostasis, to seal tissues, to close fistulas and to deliver biologics or drugs.
When fibrin and thrombin are made to mix, a coagulum is formed where the platelets interdigitate with the forming fibrin web, developing a gel with adhesiveness and strength materially greater than the plasma alone. Because of the rapid clotting propensity, it is necessary to keep the two liquid constituents separated and only mixed at the distal end of the applicator. Numerous tissue adhesive applicators have been developed, such as those described in U.S. Pat. No. 4,040,420 to Speer, U.S. Pat. No. 4,359,049 to Redl, U.S. Pat. No. 4,733,666 to Eibl, U.S. Pat. No. 4,826,048 to Skorka, U.S. Pat. No. 4,874,368 to Miller, U.S. Pat. No. 4,902,281 to Avoy, U.S. Pat. No. 4,978,336 to Capozzi, U.S. Pat. No. 5,368,563 to Lonnemann and U.S. Pat. No. 5,474,540 to Miller. A variety of these types of applicators exist including internal swirl or mixing chamber applicators and external combining applicators, such as external swirl applicators and external spray or stream overlapping applicators.
The Skorka '048 patent, the Capozzi '336 and '315 patents concerns swirl or other pre-ejection mixing applicators where mixing is performed by squirting or otherwise forcing the two non-homogeneous fluids into a swirl or other mixing chamber where the fluids mix to some degree based upon turbulence in the swirl chamber and the material properties and are thereafter ejected from the applicator. The mixing occurs inside the applicator and, thus, time is critical, as it must be ejected prior to coagulation. In certain applications, such as where one or more of the solutions or fluids is thick or high viscous, internal swirling results in only marginal or partial mixing, while in other applications, such as where all of the solutions or fluids are thin or not highly viscous, substantial and effective mixing occurs.
In contrast, the applicators described in the Speer '420, the Miller '368 and the Avoy '281, the Lonnemann '563 and the Miller '540 patents are external combining applicators. Here, the two solutions are brought into contact with one another at the point of use or functional tissue adhesive creation. External combining eliminates premature mixing problems. However, with many external combining applicators, thorough mixing of the solutions does not occur and, instead, only adjacent portions of the solutions mix or combine well large percentages remain unmixed or uncombined. This results in inefficient and somewhat uncontrolled coagulation. The Lonnemann '563 patent owned by applicant's assignee is considered to be a significant advance in external combining applicators. It provides an external swirling pattern where the two fluids overlap one another resulting in improved fluid mixing.
In copending application Ser. No. 10/863,631, filed Jun. 8, 2004, and entitled “Spray Applicator”, there is described a medical fluid delivery system which expels two liquid components, at least one of which is reactive, from separate syringes while simultaneously releasing a pressurized fluid, such as a compressed gas, around, adjacent to or proximate the reactive components resulting in thorough mixing of the reactive components as well as propulsion thereof in a commingled stream onto a surgical site. The teachings of such application are hereby incorporated by reference. The teachings of that application, however, do not address a further problem where such a gas propelled stream of reactive liquids, such as fibrin and thrombin are to be used in a laparoscopic procedure.
In laparoscopic procedures, a series of holes are surgically created in the abdominal wall with one to accommodate a camera and others to accommodate a cannula through which a working instrument, such as a laparoscopic scissors, forceps are inserted for grasping and cutting target tissue. It is common practice to insufflate the abdominal cavity by introducing a gas through one of the trocars, thereby expand the abdominal cavity to aid in viewing and manipulating internal organ structures. The trocars include a self-closing seal for preventing loss of insufflation gas while allowing penetration by the surgical instruments employed. The pressure employed in insufflating is generally about 15 mmHg and the introduction of additional gas by way of a laparoscopic spray applicator could result in over-inflation and distension of the abdominal wall. Means must, therefore, be provided to insure that this does not occur.